Navegando por Assunto "Antenas"

Agora exibindo 1 - 3 de 3

Acesso aberto (Open Access)
Acoplamento de modos guiados em cabos de pares trançados utilizando antenas com simetria radial no cenário terabit DSL
(Universidade Federal do Pará, 2020-03-26) SOUSA, Brenda Penedo Tavares de; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
The development of data transmission standards and access technologies has always been linked to the need to supply high data rates. Thus, technologies already implemented, such as the DSL (Digital Subscriber Line) system that uses twisted pairs for transmission, have been adjusting to support this growing data demand. In DSL systems, the twisted pairs are used as a transmission line, using the transverse electromagnetic mode (TEM). However, the physical limitations of the twisted pair as a transmission line prevent the system from achieving higher rates, needed to support fifth generation (5G) applications. Recently, it was proposed to use other transmission modes in the twisted pair, the higher order guided modes, as an alternative for this structure to be able to support transmission rates of the order of Terabits per second, having been termed as the Terabit DSL technology (TDSL). However, one of the challenges for this implementation is the coupling of the guided modes in the twisted pair, since they are not widely explored in the context of the propagation of higher-order guided modes, as simpler waveguides, such as Sommerfeld and Goubau. In this scenario, this dissertation aims to evaluate the coupling of the radiated signal between an antenna with radial propagation and the twisted pair cable, analyzing the electromagnetic behavior of structures. Considering that the twisted pair cable does not have a closed analytical model for the behavior of higher order modes, which propagate along these structures, all the results were obtained from numerical simulations in the software HFSS (High Frequency Structure Simulator).These results are in terms of the scattering parameter of the antenna and the electromagnetic field in the cable, making it possible to evaluate the coupling efficiency, the signal guidance and to predict the transmission rate available to users. The results obtained showed that the coupling between the antenna and the unshielded twisted pair cable reached levels of up to 83.83 % at frequencies of 0.15 THz, demonstrating a high coupling efficiency when compared to simpler scenarios in the literature, reaching levels on average 67 %. It was found that the use of these cables for data transmission is effective, managing to deliver rates of up to 1.737 Tbps in cables of up to 10 meters, while the rate forecasts for the TDSL scenario that consider the 100 % coupling reach levels of 2.013 Tbps.
Acesso aberto (Open Access)
Análise de desempenho de redes de acesso G.mgfast e fronthaul 5G baseado em cabos coaxiais
(Universidade Federal do Pará, 2019-05-27) FREITAS, Marx Miguel Miranda de; NUNES, Diogo Lobato Acatauassú; http://lattes.cnpq.br/1972007941497086; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
This work explores two possibilities of harnessing mature cabling technologies used in broadband networks of 4th generation systems in emerging next generation applications. Specifically, two proposals for using the cabling structure of Hybrid Fiber Coax and SAT TV (Satellite Television) systems are evaluated. The first one, as support in 5G network analog transport networks (fronthaul). The second evaluates the use of coaxial cables in access networks G.mgfast (Multi Gigabit G.fast). In the firs one, It is shown the relationships between the data rates and the number of antennas reached by the coaxial cable RG06, under a fixed power level and a target signal noise condition, considering different distances and two configurations of radio signals. It is shown that in the 5G analogue fronthaul analyzed, rates higher than 40 Gbps can be obtained in a RG06 coaxial cable, giving support to 140 antennas, meeting 3GPP transmission criteria. The second solution proposes a process to reduce power consumption in the network, by adapting the transmission power in the coaxial network, with higher bit load in the initial frequencies of the spectrum. Links with RG59, RG06 and RG11 coaxial cables are analyzed, considering rates ranging from 5 Gbps to 10 Gbps and two types of bit loading algorithms. It is shown that with these procedures the power saving obtained in single link with 100 m coaxial cable can be used to power another 28 cables of 50 m. On the other hand, it is shown that the power reduction is not relevant, from the point of view of redistribution, in cables whose length is less than or equal to 25 m.
Acesso aberto (Open Access)
SIMPLARCOM: simulador para planejamento de redes de comunicação sem fio utilizando realidade virtual e modelos de propagação
(Universidade Federal do Pará, 2014-04-25) PINHEIRO, Diego Carneiro; RIBEIRO FILHO, Manoel; http://lattes.cnpq.br/9329438229733907
This simulator is formed by the junction of Virtual Reality techniques with propagation models, developed through the studies of radio enlace, describing the loss that the transmitted signal suffers along the way in the environment. The Simulator has two modules. The first allows the creation of virtual environment with the placement, on a ground, buildings, trees, cars, antennas and other primitives that allow the construction of a customizable three-dimensional environment. The second module allows the configuration of the parameters related to antenna signal propagation as power, frequency, gain, etc., and also selects the propagation model for the simulation execution. Within this second module, there is a submodule responsible for coverage area planning study composed by antennas, in other words, this submodule simulates the distance that each antenna in the scenario can reach and generates its coverage area. To demonstrate the Simulator efficiency was created two virtual environments for testing. A scenario representing an urban environment where employed a classic propagation model, Okumura-Hata to small and medium-sized cities, and a wooded three-dimensional environment using a specific model for propagation simulation of densely wooded regions, developed at the Federal University of Pará called Lyra- Castro-UFPA.